Shared Resources Laboratories (SRL) are fundamental cornerstones of the 2003 NIH Roadmap. Often referred to as core laboratories, SRLs are the most cost-effective approach to provide a broader range of scientific expertise from skilled technology scientists and advanced instrumentation than would be feasible or economically-viable for individual laboratories. Best practices for a Flow Cytometry SRL include: 1) stable and consistent financial support, 2) a highly qualified scientific director (head), 3) policies conducive to recruitment and retention of highly skilled technical staff, 4) user training and staff continuing education, 5) a quality control program for the instruments, 6) support for research and development, 6) overview of satellite facilities), and 7) at a minimum, a 5-year plan for future technology expansion and operation. The NIA Flow Cytometry Unit (LMG) functions as a Shared Resource Laboratory (SRL) to provide analytical flow cytometric analysis and cell sorting services to the entire NIA IRP. The core was judged to be exceptional from the 2011 BSC review. The core is used by investigators from every bench-science based laboratory in the Baltimore IRP. 99.5% of the core usage, facilities, and publications coming from the core are in support of NIA intramural scientists. Laboratory usage has increased over the years as sorting capacity has increased along with new research initiatives by IRP labs, such as sorting murine and human muscle stem cells. FY12 core usage was at 102% of capacity 2011 capacity and until the move to the BRC was 101% for FY2013. Sorting is heavily scheduled by users requiring multiple instruments (2-3) for the full day or greater in order to process >300 million cells. Some investigators experimental protocols require specific instruments. Besides the current core users, two additional laboratories have projected substantial sorting needs (50-100 sorts and >400 million cells for processing) in the near future, obligating full use of the sorting capacity for 4 days per week with 1 day open for other laboratories. The core provides cutting edge, state-of-the-art flow cytometry for multi-parameter (polychromatic) analysis and sorting. Flow cytometry instrumentation has a 5 7 year lifespan and to plan for the future, the IRP has made major instrument purchases in 2008 with the acquisition of an iCyt Reflection HAPS (Highly Automated Parallel Sorting) instrument that is housed in a Baker BL-2 hood for sorting adeno- and lentivirus-infected animal and human cells. Each HAPS is configured differently to provide the maximum flexibility for investigators experimental design. In 2013 with the move to the BRC, the obsolete (purchased in 2001 with parts no longer widely available) MoFlo high speed cell sorter was upgraded to an digital version incorporating 405nm, 532nm, and 561nm lasers in addition to an 640nm laser and the 90-5 water-cooled argon and krypton-ion lasers that were retained from the analog instrument. We are currently experiencing problematic issues with this instrument. The laboratory space for the BRC facility was designed to house the Aria SORP (4 lasers) in a dedicated BL-3 room to be able to sort live non-human primate cells. Service contract costs account for approximately 80% of the annual operating budget and will increase in 2014 as the MoFlo comes out of its warranty period. The mission of the NIA flow cytometry shared resource lab is to enhance the scope and quality of the research within the IRP by providing all investigators with the expertise necessary to employ its advanced technologies optimally for their research. This includes having a highly qualified director (with 32yrs flow cytometry core experience), active consultation on experimental design, implementation, and data interpretation, originating new procedures, suggesting or performing the critical experiments that take their research in new directions, and in advancing technological developments in the field. Users can visit the core web page, in use since 1999. The NIA Flow Cytometry Unit is organized and managed in a manner consistent with the policies and staffing levels of flow cytometry cores at extramural academic institutions and at NIH. A survey (updated March 2011) of these sites (9 NIH, 133 academic, total 142) indicates that in 91.4% of the cores, sorting is performed only by core personnel. The reason for this is twofold: 1) it is the most efficient way to provide reliable services to the IRP (i.e. minimizing the possibility of instrument abuse by users and thus removing the cascading effect that this has on the ability to complete the next scheduled users sort, especially when the core is heavily booked). 2) neither the MoFlo nor iCyt are turnkey black box, menu-driven instruments (nor is the Aria II in the case of the ability to troubleshoot). Sort usage has expanded in parallel with instrument capacity. For FY11 and FY 12, the core ran at 102% of capacity. Relevance to the NIA IRP Program In addition to the level of core utilization by investigators, measurement of the effectiveness and value of the core to IRP productivity is evident from the 157 publications generated by NIA investigators using flow cytometry/sorting as an integral part of their research since the cores inception in 1999. A partial list of these includes J Immunology (10), BMC Immunology (2), J Exp Med (1), Cellular Immunology (2), Immunity (1), Nature Immunology (1), Blood (2), Cancer Res (1), PNAS USA (3), Endocrinology (1), PLOSone (3), DNA Repair (3), Mol Cell Biol (3), EMBO J (1), and Nature (1), other journals (43). 98.5% of research papers using core services are from NIA IRP investigators.